This invention relates to a linear motor elevator system in which a linear motor is used as a drive unit for driving an elevator car in a hoistway.
A linear motor elevator system having a linear motor drive unit is disclosed in Japanese Patent Laid-Open No. 57-121568.
FIG. 10 is a schematic side view of one example of a linear elevator system in which a linear synchronous motor (LSM) is used as a drive unit, and FIG. 11 is a schematic plan view of the elevator system illustrated in FIG. 10.
In FIGS. 10 and 11, a rope 3 extending around a first and a second sheaves 1 and 2 has connected at one end thereof an elevator car 4 and has connected at the other end a counter weight 5. The elevator car 4 and the counter weight 5 are both movable members disposed and movable within a hoistway 6. Within the hoistway 6, vertically extending car guide rails 7 are securely attached to an inner wall through rail brackets 8 so that unillustrated guide rollers mounted to the elevator car 4 is in guided engagement with the guide rails 7 and so that the elevator car 4 is vertically movably guided along the guide rails 7. Similar guide rails 9 for vertically movably guiding the counter weight 5 through guide rollers (not shown) on the counter weight 5 are securely attached to the inner wall of the hoistway 6.
The elevator car 4 is provided with a car door 4a, and in the corresponding position of the hoistway 6, a landing floor door 6a is provided.
The elevator car 4 also has mounted on side walls thereof field magnets 10. The inner wall of the hoistway 6 has mounted thereon armatures 11 each disposed in a facing relationship with respect to the field magnets 10 on the car 4. The armatures 11 are mounted through mounting brackets 12 to extend throughout the hoistway 6. The field magnets 10 and the armatures 11 together constitute a linear synchronous motor.
In the linear motor elevator system in which the conventional LSM as above-described is used, a vertical electromagnetic drive force which drives the elevator car 4 is generated by generating a progressive magnetic field acting on the field magnet 10 in the elongated vertical armature 11 by exciting the armature 11 in the hoistway 6. Accordingly, the armature 11 must have armature windings which extends over an entire length of the vertical hoistway and which therefore increases the manufacturing cost of the elevator system.
FIG. 12 is a schematic side view of one example of a conventional linear motor elevator system employing a conventional linear induction motor (LIM) as a drive unit, and FIG. 13 is a schematic plan view illustrating the linear motor elevator system shown in FIG. 12.
In FIGS. 12 and 13, a plate-shaped secondary conductor 15 made of aluminum for example and vertically extending along the hoistway 6 is secured through a bracket 16 to inner side walls of the hoistway 6. The elevator car 4 has mounted on both sides thereof primary windings 17. It is seen that two primary windings 17 are used in pair on each side of the elevator car 4, in which two primary windings 17 are supported in an opposing relationship to each other with a space defined therebetween. The secondary conductor 15 having a thickness t.sub.1 extends into the space between the primary windings 17 with gaps g.sub.1 and g.sub.2 defined on each side of the secondary conductor 15. The secondary conductor plate 15 and the primary windings 17 together constitute a linear induction motor (LIM). Although not illustrated, the electrical power to the primary windings 17 mounted on the elevator car 4 is supplied from an external power source through unillustrated travelling cables and/or sliding contact shoes.
When an a.c. power is supplied to the primary windings 17 thereby generating a magnetic field having magnetic fluxes that move as the time lapses, eddy currents are generated in the surfaces of the plate-shaped secondary conductor 15. Therefore, because of the electromagnetic interactions between the progressive magnetic field and the eddy currents, a thrust or a drive force which drives the elevator car 4 is generated in the linear induction motor.
In the linear induction motor elevator system as above described, the magnetic gap which is the sum of the gaps g.sub.1 and g.sub.2 and the thickness t.sub.1 of the secondary plate conductor 15 is inevitably defined between the opposing primary windings 17, which causes the power factor of the linear induction motor to decrease, making the linear induction motor to be large sized.